The present invention relates to a sleeve structure of an office chair. The sleeve structure includes a sleeve body in which a pneumatic bar is fitted nearly without clearance existing therebetween. When the pneumatic bar suffers a load or a torque by different inclined angles, the office chair is always stably and safely supported without swinging.
Different types of office chairs (such as wooden chairs, iron chairs, sofa chairs, etc.) are widely used in various offices. Especially, the sofa office chairs are most popularly used in the offices. Each sofa office chair is supported by a support stem including a sleeve structure having a plastic flexible sleeve body in which a pneumatic bar is directly fitted. As shown in FIG. 4, the sleeve body with the pneumatic bar is fitted and fixed in a bar seat tube to form the support stem. Such sleeve structure has the following shortcomings:
1. The plastic flexible sleeve body is directly and not tightly fitted around the pneumatic bar. When the pneumatic bar suffers a load or a torque, the pneumatic bar will squeeze toward the sleeve body to deform the same and expand the sleeve hole thereof. As a result, a clearance will be produced between the sleeve body and the pneumatic bar and the office chair will tend to swing when loaded. This makes a user uncomfortable and unsafe when sitting on the office chair.
2. In the conventional sleeve structure of the office chair, the plastic flexible sleeve body is subject to permanent expansion and deformation after a long period of squeezing of the pneumatic bar. Therefore, the clearance between the pneumatic bar and the sleeve body will be more and more expanded. This makes the office chair unstably supported and liable to swing when suffering a heavy load. Moreover, when a user lies on the back of the office chair by a large inclined angle, the pneumatic bar and the sleeve body may be unable to bear the weight of the user and fall down.